The invention relates to a cleaning device to be used in a electrophotographic copy machine or a printer, and an image forming method and an image forming apparatus using the cleaning device.
Recently, an organic photoreceptor, hereinafter referred to a photoreceptor, containing an organic photoconductive substance is most widely used as an image carrier to be used in an electrophotographic image forming apparatus. The organic photoreceptor has advantages over another photoreceptor in that the organic photoreceptor responding various light sources from visible rays through infrared rays can be easily developed, a material without environment pollution can be selected and the material can be produced with a low cost. However, the organic photoreceptor has a shortcoming that such the photoreceptor is weak in the mechanical strength and tens to occur a degradation or formation of damage on the photoreceptor surface when the photoreceptor is subjected to many times of copying or printing operations.
Moreover, a remaining toner remained on the photoreceptor after transfer of the toner image to an image receiving member is difficultly removed since the contact energy of the photoreceptor with the toner for developing the electrostatic latent image formed on the photoreceptor is large. Consequently, various problems tend to be raised on the cleaning of the photoreceptor surface.
Besides, in the electrophotographic image forming method, a digital method is become the main current of the image formation technology accompanied with the progress in the digital technology. It is standardized in the digital image formation that a fine dot image of one pixel such as 400 dots per inch (dpi) is made actual image. Accordingly, a high quality image forming technology is required by which such the fine dot image can be reproduced with a high fidelity.
On the other hand, various methods for raising the mechanical strength of the photoreceptor surface have been proposed as a countermeasure against the degradation of the organic photoreceptor surface accompanied with the cleaning.
Japanese Patent Publication Open to Public Inspection No. 9-258460 proposes a photoreceptor having a surface layer of polycarbonate resin having a high hardness for reducing the surface abrasion. Such the photoreceptor having the polycarbonate resin layer is different from the usual photoreceptor in that the friction force between a cleaning blade, hereinafter simply referred to a blade and the surface of photoreceptor, since the surface abrasion of the photoreceptor by the cleaning is small. Consequently, an incompletely cleaning tends to be occurred by the turning over of the blade and the toner slipping through the blade caused by vibration of the blade.
Another one of the methods is technology regarding the production of toner. Currently, a crushed toner is mainly used to form an electrophotographic image, which is produced by mixing and kneading binder resin and pigment, and crushing the kneaded mixture to prepare a toner powder and classifying the crushed powder. However, there is a limit on the unifying of the size of such the toner particles, and the uniformities of the size and the shape of the toner particles are insufficient. It is difficult to achieve a sufficient high quality of image by an electrophotography using such the crushed toner.
Recently, an electrophotographic developer or an image forming method using a polymerized toner is proposed as a means to unify the size and the shape of the toner particles. The polymerized toner is produced by dispersing a raw material toner in an aqueous medium and polymerizing the dispersed monomer, thus a toner can be obtained composed of particles unformed in the size and the shape thereof.
However, a technical problem is newly raised when the polymerized toner is used in an image forming apparatus having the organic photoreceptor. The polymerized toner is produced so that the particles each have an approximately spherical shape since the shape of the toner is formed in the course of the polymerization of the toner. As well-known, the spherical toner remaining on the photoreceptor tends to cause incomplete cleaning. Particularly, the surface of the organic photoreceptor is easily abraded and slipping of the fine toner particle through the blade in a degree so as to form no image are occurred during a long period of time when the toner is adhered in the irregularities of the surface formed by the abrasion. The toner particles slipped through the blade contaminate a charging member such as a charging wire and a charging roller and an unevenness of the image is formed in the halftone image.
Various methods have been proposed for improving the incompletion of cleaning such as the turning over of the blade and the toner slipping through the blade in the image forming method using the polymerized toner. Among them, a proposal to change the shape of the toner particle from the spherical shape to an ellipse shape and that to make irregular the surface of the toner particle are tried. However, these proposals cannot be sufficient solving means.
The object of the invention is to solve the foregoing problems and to provide a cleaning device, and an image forming method and an image forming apparatus using the cleaning device, by which the cleaning effect is maintained for a long period of time and a good electrophotographic image can be obtained without any fault in image.
It is found by the inventors that a good cleaning property can be maintained and a stable vibration of the blade can be kept by sticking a plastic member to the cleaning blade, and the foregoing problems can be solved.
The invention and the embodiment thereof are described below.
1. A cleaning device removing residual toner on a photoreceptor wherein the cleaning device comprises a cleaning blade composed of a plurality of plate materials laminated each other, the plurality of plate materials including a cleaning blade member and a plastic member each of which is mounted on a support member, the cleaning blade member being brought into contact with said photoconductor and the plastic member not being brought into contact with said photoconductor, wherein elastic modulus of the cleaning blade D1 and the elastic modulus of the plastic member D2 satisfy
16xe2x89xa6D2/D1xe2x89xa62,800. 
2. The cleaning device of item 1 wherein tensile strength H of the plastic member satisfies
1.4xe2x89xa6Hxe2x89xa635 (H: kgf/mm2). 
3. The cleaning device of item 1 wherein bending strength M of the plastic member satisfies
0xe2x89xa6Mxe2x89xa641 (M: kgf/mm2). 
4. The cleaning device of item 1 wherein length L1 of the cleaning blade member is longer than length L2 of the plastic member.
5. The cleaning device of item 1 wherein the cleaaning member and the plastic member are laminated with an adhesive layer.
6. The cleaning device of item 1, wherein the cleaning device satisfies;
0.1xe2x89xa6L2/L1xe2x89xa60.9 
wherein L1 is a free length of the cleaning blade member and L2 is a free length of the plastic member,
{fraction (1/50)} less than t2/t2 less than 1 
wherein t1 is a thickness of the cleaning blade member and t2 is a thickness of the plastic member, and
1.4xe2x89xa6Hxe2x89xa635 (H: kgf/mm2). 
wherein H is tensile strength of the plastic member.
7. The cleaning device of item 1, wherein the cleaning device satisfies;
0.1 less than L2/L1xe2x89xa60.9 
wherein L1 is a free length of the cleaning blade member and L2 is a free length of the plastic member,
{fraction (1/50)} less than t2/t1 less than 1 
wherein t1 is a thickness of the cleaning blade member and t2 is a thickness of the plastic member, and
0 less than Mxe2x89xa641 (M: kgf/mm2) 
wherein bending M is bending strength of the plastic member.
8. The cleaning device of item 6 wherein L2/L1 is 0.3 to 0.7.
9. A cleaning device removing residual toner on a photoreceptor wherein the cleaning apparatus comprises a cleaning blade composed of a plurality of plate material laminated each other, the plurality of plate material including a cleaning blade member and a plastic member each of which is mounted on a support member, the cleaning blade member being brought into contact with said photoconductor and the plastic member not being brought into contact with said photoconductor, wherein length L1 of the cleaning blade member is longer than length L2 of the plastic member.
10. The cleaning device of item 9 wherein each of the plurality of plate materials is laminated with an adhesive layer.
11. The cleaning device of item 9 wherein elastic modulus of the cleaning blade D1 and the elastic modulus of the plastic member D2 satisfy
16xe2x89xa6D2/D1xe2x89xa62,800. 
12. The cleaning device of item 10 wherein the cleaning blade satisfies one of following conditions;
0.1 less than L2/L1xe2x89xa60.9 
wherein L1 is free length of a cleaning blade member and L2 is free length of a plastic member,
{fraction (1/50)} less than t2/t1 less than 1 
wherein t1 is thickness of the cleaning blade member and t2 is thickness of the plastic member,
1.4xe2x89xa6Hxe2x89xa635 (H: kgf/mm2) 
wherein H is tensile strength of the plastic member.
13. An image forming method comprising steps of exposing a photoreceptor uniformly, imagewise exposing to form a latent image, developing the latent image by toner to form a toner image, transferring the toner image to a recording material, fixing transferred toner image and cleaning a residual toner on the photoreceptor by a cleaning device, wherein the cleaning device comprises a cleaning blade composed of a plurality of plate materials laminated each other, the plurality of plate material including a cleaning blade member and a plastic member each of which is mounted on a support member, the cleaning blade member being brought into contact with said photoconductor and the plastic member not being brought into contact with said photoconductor, and the cleaning blade satisfies one of following conditions;
0.1 less than L2/L1xe2x89xa60.9 
wherein L1 is free length of a cleaning blade member and L2 is free length of a plastic member,
{fraction (1/50)} less than t2/t1 less than 1 
wherein t1 is thickness of the cleaning blade member and t2 is thickness of the plastic member, and
1.4xe2x89xa6Hxe2x89xa635 (H: kgf/mm2) 
wherein H is tensile strength of the plastic member.
14. An image forming method comprising steps of exposing a photoreceptor uniformly, imagewise exposing to form a latent image, developing the latent image by toner to form a toner image, transferring the toner image to a recording material, fixing transferred toner image and cleaning a residual toner on the photoreceptor by a cleaning device, wherein the cleaning device comprises a cleaning blade composed of a plurality of plate materials laminated each other, the plurality of plate material including a cleaning blade member and a plastic member each of which is mounted on a support member, the cleaning blade member being brought into contact with said photoconductor and the plastic member not being brought into contact with said photoconductor, and the cleaning blade satisfies one of following conditions;
0.1 less than L2/L1xe2x89xa60.9 
wherein L1 is free length of a cleaning blade member and L2 is free length of a plastic member,
{fraction (1/50)} less than t2/t1 less than 1 
wherein t1 is thickness of the cleaning blade member and t2 is thickness of the plastic member, and
0 less than Mxe2x89xa641 (M: kgf/mm2) 
wherein bending M is bending strength of the plastic member.
15. An image forming method of item 12 wherein toner has the variation coefficient of the shape coefficient of toner particles of not more than 16 percent, and the number variation coefficient of the number size distribution of said toner particles of not more than 27 percent.
16. An image forming apparatus comprising a photoreceptor, exposing unit to form a latent image on the photoreceptor, developing unit to visualize toner image, transferring unit to transfer visualized toner image to a recording material, fixing transferred toner image on the recording material and cleaning device to clean a residual toner on the photoreceptor, wherein the cleaning device comprises a cleaning blade composed of a plurality of plate materials laminated each other, the plurality of plate material including a cleaning blade member and a plastic member each of which is mounted on a support member, the cleaning blade member being brought into contact with said photoconductor and the plastic member not being brought into contact with said photoconductor, and the cleaning blade satisfies one of following conditions;
0.1 less than L2/L1xe2x89xa60.9 
wherein L1 is free length of a cleaning blade member and L2 is free length of a plastic member,
{fraction (1/50)} less than t2/t1 less than 1 
wherein t1 is thickness of the cleaning blade member and t2 is thickness of the plastic member,
1.4xe2x89xa6Hxe2x89xa635 (H: kgf/mm2) 
wherein H is tensile strength of the plastic member.
17. The image forming apparatus of item 14 wherein contact angle xcex8 of the cleaning blade member against the photoreceptor is not less than 10 degree.
Another embodiment of the invention is described below:
1. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the front edge of the cleaning blade and the front edge of the plastic member are arranged to form a level difference so that the position of the front edge of the plastic member is farther than the position of the front edge of the cleaning blade from the organic photoreceptor.
2. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the free length of the cleaning blade L1 and the free length of the plastic member L2 satisfy the following formula 1:
Formula 1
0.1 less than L2/L1xe2x89xa60.9. 
3. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the thickness of the cleaning blade t1 and the thickness of the plastic member t2 satisfy the following formula 2:
Formula 2
⅕xe2x89xa6t2/t1xe2x89xa61. 
4. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the elastic modulus of the cleaning blade D1 and the elastic modulus of the plastic member D2 satisfy the following formula 3:
Formula 3
16xe2x89xa6D2/D1xe2x89xa62,800. 
5. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the tensile strength H of the plastic member satisfies the following formula 4:
Formula 4
1.4xe2x89xa6Hxe2x89xa635 (H: kgf/mm2). 
6. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the bending strength M of the plastic member satisfies the following formula 5:
Formula 5
0 less than Mxe2x89xa641 (M: kgf/mm2). 
7. A cleaning device having a cleaning blade for removing the toner remained on an organic photoreceptor after a toner image formed on the organic photoreceptor by developing an electrostatic latent image formed on the organic photoreceptor by a developer containing a toner is transferred to an image receiving member, wherein the cleaning device has a cleaning blade and a plastic member and the cleaning blade is contacted with the plastic member on the surface of the cleaning blade opposite to the surface of the cleaning blade to be contacted to the organic photoreceptor, and the front edge of the cleaning blade and the front edge of the plastic member are arranged to form a level difference so that the position of the front edge of the plastic member is farther than the position of the front edge of the cleaning blade from the position of the organic photoreceptor, and the cleaning blade and the plastic member satisfy the foregoing formula 1 through formula 5.
8. An image forming method comprising the steps of
developing a static latent image formed on an organic photoreceptor by a developer containing a toner,
transferring the toner image developed by the development onto an image receiving member, and
removing the toner remained on the organic photoreceptor by the cleaning device described in any one of the foregoing 1 through 7.
9. An image forming apparatus in which a static latent image formed on an organic photoreceptor is developed by a developer containing a toner,
the toner image developed by the development transferred onto a image receiving member, and
the toner remained on the organic photoreceptor is removed by the cleaning device described in any one of the foregoing 1 through 7.
10. An image forming apparatus in which a toner is used which has a variation coefficient of the shape coefficient of the toner particles of not more than 16% and a number variation coefficient of the particle size distribution of the toner particles of not more than 27%.
11. An image forming apparatus in which a toner containing toner particles having a shape coefficient of from 1.2 to 1.6 in a ratio of not less than 65% in number is used.
12. An image forming apparatus in which a toner containing toner particles each having no corner in a ratio of not less than 50% in number is used.
13. An image forming apparatus in which a toner having the organic photoreceptor comprising an electro conductive substrate and a photoreceptive layer provided on the substrate, and the surface layer of the photoreceptive layer contains polycarbonate having an average molecular weight of not less than 40,000.